CLINICAL REPORT

Intraoperative pulmonary barotrauma during ophthalmologic surgery. Case report^*

Barotrauma pulmonar en el intraoperatorio de procedimiento quirúrgico oftalmológico. Relato de caso

Affonso Henrique Zugliani, TSA^I; Flávia Claro^II; Ana Cláudia C. Mega^II; Marcelo F. Rodrigues^III; Gilblainer Ancelmé^III

^IResponsável pelo CET/SBA do H. M. Souza Aguiar
^IIAnestesiologista do Serviço de Anestesiologia do H. M. Souza Aguiar
^IIIMe₂ do Serviço de Anestesiologia do H. M. Souza Aguiar

Correspondence to

SUMMARY

BACKGROUND AND OBJECTIVES: Nowadays, severe anesthetic complications caused by the improper use of mechanical ventilators are rare. However, technical details even in recent models can be a trap for the anesthesiologist and threaten patient safety. The objective of this report was to demonstrate the importance of a careful analysis of the device to be used, as well as to detect and treat intraoperative tension pneumothorax.
CASE REPORT: A 16-year old female patient, physical status ASA I, underwent corneal conjunctival covering under general anesthesia. Anesthesia was maintained with isoflurane and controlled mechanical ventilation. No abnormalities were observed during anesthesia. At the final phase of the surgery, after mobilizing the anesthesia device to start the awakening process, the patient developed hypoxia, hypertension and ventilatory difficulties. After removal of the sterile drapes from the surgical field, subcutaneous emphysema was evident in the face, neck and upper limb. The tracheal cannula, which contained blood, was changed. A chest X-ray confirmed the diagnosis of pneumothorax that was immediately drained. Inspection of the equipment revealed the presence of a kink in the tubing connecting the inferior portion of the canister to the equipment itself caused by mobilization of the articulated arm, blocking the normal flow of gases and leading to pulmonary barotrauma.
CONCLUSIONS: The development of tension pneumothorax during general anesthesia with positive pressure ventilation should always be considered. Several factors can contribute to the development of this condition, which should be considered when they are present during surgeries. The anesthesia equipment should be examined carefully to detect potential causes of anesthetic complications.

Key Words: COMPLICATIONS: barotrauma; EQUIPMENT: Anesthesia Device, Ventilator.

RESUMEN

JUSTIFICATIVA Y OBJETIVOS: Accidentes anestésicos graves por mal funcionamiento de ventiladores mecánicos se hicieron escasos en los tiempos actuales. Sin embargo, detalles técnicos, incluso en aparatos de reciente fabricación, pueden ser trampas para el anestesiólogo y amenazar la seguridad del paciente. El objetivo de este relato de caso fue enfatizar la necesidad de un análisis de criterio del material en uso, como también detectar y tratar el neumotórax hipertensivo intraoperatorio.
RELATO DEL CASO: Paciente del sexo femenino, 16 años, estado físico ASA I, sometido al recubrimiento conjuntival de córnea bajo anestesia general. El mantenimiento se hizo con isoflurano y ventilación controlada mecánica. La anestesia transcurrió sin anormalidades. En la fase final del Procedimiento Quirúrgico, después de la movilización del aparato de anestesia para iniciar el Procedimiento de despertar, se observó un cuadro de hipoxia, hipotensión arterial y dificultad en la ventilación. Retirados los campos quirúrgicos, se vio un importante enfisema subcutáneo, involucrando la cara, el cuello y el miembro superior. Se procedió entonces al cambio de la cánula traqueal, observando la presencia de sangre en su interior. La radiografía de tórax confirmó el diagnóstico de neumotórax, que fue rápidamente drenado. La inspección en el equipo reveló un amontonamiento de la manguera que conecta la región inferior del canister al cuerpo del aparato, en función de la movilización del brazo articulado, bloqueando el flujo normal de gases y conllevando a baro trauma pulmonar.
CONCLUSIONES: El neumotórax hipertensivo durante anestesia general con ventilación con presión positiva debe ser siempre un accidente a ser considerado. Múltiples factores pueden precipitarlo, lo que exige un alto grado de sospecha siempre que estén involucrados en el acto anestésico quirúrgico. El equipo de anestesia debe ser cuidadosamente examinado para que se detecten potenciales causas de accidentes anestésicos.

INTRODUCTION

Over the last decades, anesthetic safety has been a growing concern. The state of the art of anesthetic devices and monitors has contributed for a progressive reduction in anesthetic morbidity and mortality. Severe anesthetic accidents caused by faulty mechanical ventilators are very rare when compared to their incidence in the past ^1-3. Pulmonary barotrauma and hypoxic accidents were common when miniventilators were widely used ^4,5. The objective of the present report was to call the attention of anesthesiologists to minor manufacturing defects on the equipment that can cause unacceptable accidents with severe consequences both to patients and health professionals involved with anesthesia.

CASE REPORT

This is the case of a 16 years old female patient, 1.62 m, 75 kg, physical status ASA I, who underwent corneal conjunctival covering. Anesthesia was induced with propofol, fentanyl and atracurium. Tracheal intubation was successful on the first attempt without intercurrences. Anesthesia was maintained with isoflurane/oxygen and the patient remained under controlled mechanical ventilation with a Conquest 3000 model HB ventilator. Monitoring consisted of pulse oximetry, cardioscope, capnography and non-invasive blood pressure. Anesthesia evolved without any abnormalities until the final phases of the surgery when the anesthesia equipment was mobilized to begin awakening procedures. Shortly after moving the device, the patient developed hypertension, progressive hypoxemia and breathing difficulties. Auscultation of the lungs was hindered by the weight of the patient.

At that moment, when the sterile gowns were removed from the field, subcutaneous emphysema of the face extending to trunk and upper limbs was observed (Figure 1). The presence of a laryngeal lesion was suspected and, thereafter, the patient was examined and the endotracheal tube was changed without improvement in the condition of the patient. Blood was present inside the endotracheal tube that was removed, which, associated with to all other signs, indicated the presence of a pulmonary lesion and consequent tension pneumothorax. An X-ray of the chest was requested (Figure 2) to confirm the diagnosis and the patient remained under observation for an eventual thoracic puncture with a needle if her clinical condition worsened. After confirmation of bilateral pneumothorax, intercostal drainage with underwater seal was instituted. Careful inspection of the equipment revealed the presence of a kink in the tubing connecting the lower aspect of the canister to the device itself, blocking the flow of gases (Figure 3). This happened after mobilizing the device and the arm of the canister. The patient was discharged from the hospital three days later without further complications.

DISCUSSION

Intraoperative tension pneumothorax is a severe complication. It demands immediate diagnosis and treatment due to hemodynamic and respiratory repercussions. The progressive increase in intrathoracic pressure caused by air-trapping between the pleural surfaces leads to a progressive reduction in pulmonary expansion and venous return to the right side of the heart. It can also cause kinking of the large vessels in the case of unilateral tension pneumothorax, as the mediastinum is deviated to the contralateral side. The development and evolution of this occurrence are favored and worsened by pulmonary ventilation with positive pressure. Several factors can cause intraoperative uni or bilateral tension pneumothorax secondary to pleural and/or parenchymal lung lesions. Among them are:

• Invasive manipulation close to the pleura, pulmonary parenchyma, or diaphragm, which can cause accidental lesions to those structures ⁶.
• Pre or intraoperative deep venous puncture, both on the subclavian and internal jugular veins ^7,8.
• Supra or infraclavicular brachial plexus block⁹ and intercostal, interpleural and epidural block.
• Closed thoracic trauma with or without fracture of the ribs ¹¹.
• Cold steel or firearm lesions, not necessarily in the thorax, because the trajectory can be unpredictable.
• Barotrauma caused by hypertensive pulmonary ventilation, voluntary or accidental. The former can be caused by defective expiratory valves, safety valves, or even bacterial filters ¹².
• Bleb rupture, secondary to congenital or acquired abnormalities, on the surface of the pulmonary parenchyma in the presence of mechanical ventilation with positive pressure ¹³.

Air leaking through a rupture of the parietal pleura or bronchial structure leads to the development of subcutaneous emphysema, which can reach large proportions, affecting the entire surface of the body.

In the event of any one of the occurrences mentioned above, which have the potential to cause a pneumothorax, the anesthesiologist should be alert and have a high degree of suspicion to detect this event ¹⁴. Early detection of jugular vein filling or increase in central venous pressure, hemodynamic instability with hypotension that cannot be explained by the anesthetic-surgical procedure, decreased breath sounds, reduction in cardiac sounds, hypertympanism of the thorax, increased airways pressure and the presence of subcutaneous emphysema are fundamental for a good prognosis.

Thoracic decompression should be done immediately, without radiological confirmation in severe cases. In those cases, decompressing puncture with a wide gauge needle in the midclavicular line of the second intercostal space should be done until conventional drainage under water seal can be instituted. In cases of diagnostic uncertainty, bilateral thoracic punctures should be performed. A disposable thoracic puncture kit should be readily available.

The anesthesia equipment should be verified regularly, examining the entire valvular system and especially the safety valve, which guarantees the elimination of gases with increasing pressure.

In the case presented here, detection of this complication was difficult because it only manifested itself when the articulated arm of the canister was mobilized. The tube connecting its inferior surface to the device was excessively long and composed of a material that allowed it to kink when the arm of the canister was manipulated. This blocked the exhaust of excess gases from the circuit and hindered the reading of airways pressure (Figure 4).

The development of the complication at the end of the surgery facilitated the diagnosis because, besides the hemodynamic and respiratory compromise, subcutaneous emphysema of the face and upper limbs was evident as soon as the sterile surgical drapes were removed. Although hypoxemia reached borderline levels (SpO₂ 70), it was decided to wait for the radiological confirmation before instituting the proper treatment since the picture did not evolve to the point of requiring immediate thoracic puncture.

This accident was reported to the Technical Standards Commission of the Sociedade Brasileira de Anestesiologia and the manufacturer of the equipment, who changed the device mentioned here.

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Correspondence to:
Dra. Flávia Claro da Silva
Rua Garibaldi, 163/304 - Bl. 01 – Tijuca
20511-330 Rio de Janeiro, RJ
E-mail: clinica.dor@inca.gov.br

Submitted em 22 de maio de 2006
Accepted para publicação em 9 de outubro de 2007

* Received from Hospital Municipal Souza Aguiar, Rio de Janeiro, RJ